1. Field of the Invention
The present invention relates to the field of devices for manually controlling a machine, coupled with a handle making it possible to grasp the machine. In particular, the device makes it possible to control sensitively and without fatigue a control device of one of the controlled systems of this machine.
2. Description of the Related Art
A considerable grasping force with the hand on the handle of a machine is usually necessary to allow a correct holding of the machine and its use in total safety. It is difficult to reconcile a vigorous grasping of a handle of a machine with at the same time exerting a coupled control on this handle.
Certain machines have a handle for holding the machine. This is the case with portable tools such as drills, brush-clearers, pneumatic drills or chainsaws. In other machines, such as motorcycles, the handle or handles are used to hold the machine. Finally there are other machines such as quad bikes, jet skis or snowmobiles, the handles of which allow the driver and user to keep himself on the machine. All these types of machines require a vigorous grasp of one or more handles.
Furthermore, certain controlled systems may be controlled occasionally at the time of a change of setpoint. This is the case for example with gearbox controls. The hand of the user is then required only occasionally, in order to control the machine. It may be permissible for the hand to slightly weaken its grip on the machine during the occasional control operation.
On the other hand, other controlled systems require being controlled continuously or virtually all the time such as controls of a carburetor or of the speed of an electric motor. A particular problem arises for manual controls that have to be actuated for a long time from a firmly grasped handle. It is necessary to reduce the risk of cramp in the muscles of the hand acted upon for the actuation of the control.
The problem of compatibility with a vigorous grasp also arises for the control of systems requiring a fine metering of the setpoint. When a new setpoint must be adapted to the reaction of the machine, the hand must be able to meter the force exerted and/or the movement of a control device.
The problem of compatibility with a firm grasp also arises for the control of a system requiring a rapid reaction from the user of the machine.
The problem of compatibility with a firm grasp arises when the action of the hand is required for a long time, even if the control of the system also has periods of inactivity. Similarly, control systems comprising means for sampling the setpoint also pose a problem of effective grasp since the hand continues to act between two samples of this setpoint.
In the field of manually controlled devices coupled with a handle making it possible to firmly grasp a machine, there are notably the handles fitted to the end of a handlebar. The two handles require a considerable grasp.
The control of a controlled system on one of these handles usually causes a grasp defect because it requires either the use of one or more fingers or that of the wrist, thereby causing an imbalance with the opposite handle. This imbalance may be relatively dangerous because it affects the gripping of the handlebar and therefore the capacity to hold oneself and to steer the machine. The system of control on the handle must also allow a precise control that is not tiring over time.
There are several types of controls coupled to handles which require either a rotation of the wrist or the detachment from the handle of one or more fingers in order to actuate the control. The most conventional controls mounted on a handle usually operate controlled systems such as throttle, brake, clutch or gearbox ratio controls.
The brake controls mounted on vehicles, for example, most frequently use an articulated lever positioned in front of the handle. This lever is usually actuated by one or more of the fingers (index finger, middle finger, ring finger, little finger) which, by closing, apply a pressure to the lever, creating via a hydraulic system a pressure which operates the braking system.
For motorcycles, there is usually a control handle device which makes it possible to operate the throttle control. This system consists of a rotary handle winding a cable which operates a throttle valve. In order to carry out this control in rotation, it is possible to leave all the fingers tight on the handle allowing a correct grasping of the latter but it is necessary to permanently bend, and sometimes do so considerably, the wrist in order to generate the control. Usually, the rest position of the control corresponds to the natural position of the wrist. The control is generated by carrying out a flexing of the wrist up to the physiological limit of the wrist. This continuous flexing of the wrist causes evident discomfort and generates an imbalance with the opposite arm which for its part keeps its wrist in a natural and non-tiring position. In addition, the flexing of the wrist physiologically affects the capacity of flexing extension of the fingers and hence the grip. Therefore, an increase in the flexing of the wrist, generating an increase in the control, not only increases the difficulty of driving the vehicle but also reduces the ability to hold and even more to grasp. In summary, the more the user accelerates and goes fast, the poorer the position of the wrist and the grip. Furthermore, during accelerations of the vehicle, by seeking to hold on more firmly, the user naturally tends to turn the handle even further and therefore to increase the acceleration of the machine which is quite dangerous.
On quad bikes, there is usually found, as a type of control coupled to a handle, a system of a rotary trigger actuated by a pressure from the thumb. This rotary trigger is usually attached to the handlebar behind the handle. It moves along a horizontal plane passing through the thumb and positioned slightly beneath the handle. In order to actuate it, it is necessary to remove the thumb from the handle, move it back toward the trigger and press it against the latter. This gives a good grip of the control device with the thumb and the possibility of correctly controlling the control device because of the use of the thumb. Nevertheless, this system has two major disadvantages. First, this control device requires a movement and a lateral extension of the thumb which is relatively painful in the long term. This lateral movement from front to rear of the thumb prevents its proximal phalanx from remaining in permanent contact with the handle and therefore participating in gripping the handle. If the proximal phalanx remains in contact with the handle it is no longer possible to carry out the control because the digit no longer has enough degrees of freedom. During control of the trigger, the gripping is left to the remaining digits (index finger, middle finger, ring finger, little finger) which increase their gripping effort in order to maintain a correct grasp, despite the loss of this essential digit, causing rapid fatigue of these digits and even cramps. Also, with this type of trigger, there is an imbalance of grip between the handle grasped by all the digits including the thumb and that grasped by all the digits except the thumb, causing an imbalance of the handlebar. These imbalances of hold and of steering are the main disadvantages of such a system.
On jet skis, the throttle is usually controlled by a small lever also called a trigger articulated in front of the handle and actuated by pulling it with the index finger. It is thus possible to firmly hold the handle with the thumb underneath, allowing a better grip than the trigger but the user loses the use of the index finger that is occupied in managing the control and that no longer participates in the grip of the handle. This loss of the index finger makes it necessary to increase the effort on the other digits (middle finger, ring finger, little finger) in order to compensate for the imbalance of effort with the other handle which for its part has all these digits for the grip. In addition, the index finger not being the strongest finger for actuating a control which is sometimes hard, there is therefore often a premature fatigue of the muscles of the index finger and even cramps. The little finger, because of its small muscular capability, does not participate significantly in the grip. Only the middle finger and the ring finger then participate in the grip of the upper portion of the handle, which is clearly insufficient. This trigger device causes a general increase in the fatigue of the fingers either due to the management of the control device or due to an increase in the gripping effort. There is also the problem of imbalance between the handle using all the fingers for the grip and that which uses only some of them, again causing a problem of holding the handlebar and of operating the steering.
There are also systems of controls coupled to a handle on portable tools which often use control methods similar to those mentioned above. On certain tools also using a handlebar, there are the same problems as those mentioned for vehicles. On the tools, there are handles that include a trigger of the joystick or firearm type. When the tool is gripped, the user squeezes the trigger and operates the control. If the user no longer desires to operate the control, he has to release the grip by opening one or more fingers, causing a weaker grip.
Patent application WO 2006/091 197 describes a trip lever for a bicycle. The device described comprises a ratchet mechanism between the handle and the trip lever. To act on the lever, the user must open the thumb, stop gripping the handle with the thumb, and draw the thumb downward in order to reach the lever. After actuating the lever, gripping the handle is again possible when the thumb has left the lever.
Application EP 1 312 541 describes a gear change device for a bicycle. Here again, the cyclist must raise the thumb and separate it from the handle in order to reach the gear lever. A disadvantage that is common to the levers described in both of the above patent applications is that the actuation of the control device is accompanied by a weakening of the grip of the handle. In addition, the type of lever is an occasional control system and does not make it possible to control continuous control systems.